Energy exhaust from tokamaks: Problems and solutions

Investigation of the edge plasma appears to be one of the key problems for tokamak design. The problem of the heat and particle removal from the react or are supposed to be solved by means of magnetic diverters. Their main mis sions are to accommodate the power outflow, to control the spatial location of the radiative zone, the helium exhaust, the impurity content in the mai n plasma, and to withstand the major energy loss in the eventuality of a di sruption energy quench. In the paper different approaches to magnetic divertor design are analyzed. However, emphasis is put an high recycling radiative ITER-Iike divertor. R esults of numerical modeling of the edge plasma are presented along with cu rrent experimental results achieved both at tokamaks and linear simulators. It is shown that there is a good agreement between the experimental result s obtained at linear simulators and the theoretical predictions obtained by means of "gas box" divertor model, which includes ionization, charge-excha nge, and 3-body and molecular advanced recombination.